JPH0124201B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a combustion furnace and its combustion furnace that can save energy by directly and effectively utilizing thermal energy contained in combustion gas discharged outside the furnace to heat a heated object. The present invention relates to a ventilation control method.

A heat-resistant material such as metal or ceramic is formed into a breathable form such as a mesh, honeycomb, fibrous, porous, etc., and this solid (hereinafter referred to as breathable solid) is used to absorb the combustion exhaust gas in the combustion furnace. By placing the combustion gas in the passageway, combustion gas flows through the air-permeable solid to heat the air-permeable solid to a high temperature by convective heat transfer, and the thermal energy radiated from the high-temperature air-permeable solid is transferred to the air-permeable solid. It is already known that energy can be saved by using combustion gas to heat an object placed inside the furnace facing the solid, and by lowering the temperature of the combustion gas and discharging it into the flue. The continuous heat treatment furnace shown in FIG. 1 is an example of this, and in the figure, 1 is an object to be heated, 2 is an inlet thereof, 3 is an outlet, 4 is a conveyor roller that supports the object to be heated,
5 is a burner provided on the furnace wall, and 6 is a flue.
The breathable solid 7 is installed on the ceiling of the furnace connected to the flue 6, and the combustion gas generated by the burner 5 is caused to flow in two directions at the entrance, passing through the breathable solid 7 and being discharged into the flue 6, thereby achieving the ventilation. The radiant heat of the solid solid 7 is used to preheat the object 1 to be heated. However, when the gas permeable solid 7 is provided facing the heated object 1 and covering a wide area (particularly elongated in the exhaust gas flow direction), the portion of the gas permeable solid 7 near the furnace inlet 2 and the portion near the burner 5 It is not possible to arbitrarily control the flow rate (passage rate) of the combustion gas in this section, and the temperature of the combustion gas discharged from the flue section does not reach the lowest level. Therefore, the sensible heat of the combustion gas cannot necessarily be effectively recovered.

The present invention has been made in view of the above, and includes a damper that can control the flow rate of combustion gas in accordance with the section of the gas permeable solid on the downstream side of the gas permeable solid, so as to most effectively generate sensible heat from the combustion gas. The purpose is to make it possible to recover energy and to further improve energy conservation in combustion furnaces.

Next, an embodiment of the present invention will be described with reference to FIG.
Note that in FIG. 2, the same reference numerals as in FIG. 1 indicate the same parts. In this combustion furnace, a damper 8 is provided on the downstream side of the permeable solid 7 to partition approximately half of the permeable solid 7 in the longitudinal direction from the flue 6, and a thermocouple 9 is installed in the flue 6 to detect the temperature of the combustion gas. establish. Then, the temperature measurement signal of the thermocouple 9 is input to the control device 10, and a command is given to the actuator 11 to control the opening degree of the damper 8 so that the measured temperature becomes the lowest. That is, for example, the opening degree of the damper 8 is changed by a predetermined value based on a signal from the control device 10 at regular intervals, and as a result, it is detected whether the temperature of the combustion gas measured by the thermocouple 9 has increased or decreased compared to before. , the opening degree of the damper 8 is controlled so that the temperature is maintained as low as possible. Incidentally, when the combustion amount of the burner 5 suddenly changes, it is detected by the flow meter 13 installed in the fuel supply pipe 12, and the optimum opening degree of the damper 8 is searched regardless of the time. By providing the damper 8 in this way, the air pressure in the downstream space 14 of the breathable solid 7 partitioned off by the damper 8 increases. For this reason, the burner 5 of the breathable solid 7
The ratio between the amount of combustion gas flowing through the portion 7a closer to the inlet 2 and the amount of combustion gas flowing through the portion 7b closer to the inlet 2 changes as the opening degree of the damper 8 changes. However, in the present invention, the flow rate of the combustion gas flowing through the breathable solid is controlled so that the temperature of the combustion gas when discharged into the flue 6 is as low as possible. Utilizing its characteristics, it can effectively absorb the sensible heat of combustion gas.

FIG. 3 shows another embodiment of the present invention, in which vertically sliding dampers 8a and 8b are provided at positions that divide the permeable solid into approximately three equal parts in the longitudinal direction. are the dampers 8a, 8
Actuator b, 16a and 16b are water sealing mechanisms for preventing gas leakage from those parts, and 17 is a furnace pressure damper installed in the flue 6 to control the atmospheric pressure in the furnace. By adjusting the opening degree of the flue 6, the total amount of combustion gas passing through the flue 6 is controlled. In addition, the same reference numerals as in FIG. 2 indicate the same or equivalent parts. In this embodiment, the air-permeable solid 7 is divided into three sections, and the air pressure on the downstream side of each section can be controlled, so that more precise control is possible than in the previous embodiment.

In addition, in the embodiment shown in FIG.
8b, three parallel lines 19a, 19b,
19c, and a damper 20a,
By providing 20b and 20c, the flow rate of combustion gas in each system can be independently controlled. In this way, the ratio of combustion gas passing through each section of the breathable solid can be more freely controlled. In this case, the total amount of combustion gas discharged into the flue 6 can be controlled by controlling the opening degree of each damper 20a to 20c. By controlling only the ratio at which the gas passes through each compartment, the combustion gas is discharged to the flue 6 and the temperature when all the gases are mixed becomes the lowest. Energy saving can be achieved.

As described above with respect to the embodiments, the present invention makes it possible to make the most effective use of the characteristics of the air-permeable solid by controlling the flow rate of combustion gas passing through the air-permeable solid in accordance with the compartments of the air-permeable solid. Therefore, it is extremely useful for saving energy in combustion furnaces.

In all of the above embodiments, the air-permeable solid is partitioned in the furnace length direction, but by partitioning the air-permeable solid in the furnace width direction, the air-permeable solid is partitioned in the furnace width direction so that the radiant heat can always be effectively radiated to the heated object directly below. The amount of combustion gas passing through each part may be controlled.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a conventional continuous heat treatment furnace equipped with a permeable solid, FIG. 2 is a longitudinal sectional view of a continuous heat treatment furnace showing an embodiment of the present invention, and FIGS.
The figure is a partial vertical sectional view of a continuous heat treatment furnace showing another embodiment of the present invention. 1... Heated object, 5... Burner, 6... Flue, 7
...Breathable solid, 8, 8a, 8b, 20a, 20
b, 20c...damper, 9...thermocouple, 10...
Control device.

Claims (1)

[Scope of Claims] 1. A flue is provided with a breathable solid that converts the heat of the combustion gas into radiant heat by causing the combustion gas in the furnace to flow through it, and an object to be heated is placed facing the breathable solid. 1. A combustion furnace comprising: a damper provided downstream of the permeable solid, the damper capable of controlling the flow rate of combustion gas in accordance with the section of the permeable solid. 2. A combustion furnace in which a flue is provided with a breathable solid that converts the heat of the combustion gas into radiant heat by flowing the combustion gas inside the furnace, and a heated object is placed facing the breathable solid. , a damper is installed downstream of the air-permeable solid to control the flow rate of the combustion gas according to the area of the air-permeable solid, and each damper is installed so that the temperature of the combustion gas when discharged into the flue is the lowest. A method for controlling a combustion furnace, characterized in that only the ratio of combustion gas flowing through the permeable solid in the compartment is controlled by adjusting the opening degree of the damper.